Method and system for minimizing the connection set up time in high speed packet switching networks

For use in a node in a packet switching communication network having a plurality of nodes interconnected by transmission links, each node having an adapter for receiving and transmitting data packets, a connection setup system for establishing a connection between an origin node and a destination node, said connection setup system comprising:

• a routing database for storing previously established paths between different ones of said nodes including characteristics of the previously established connection paths;
• a path selection subsystem responsive to a connection request for determining whether said routing database contains a previously established stored connection path which is suited to cater requirements of the connection request, said path selection subsystem being responsive to a determination that a suitable path exists in said routing database to establish the requested connection using the previously established connection path, said path selection subsystem being responsive to a determination that no suitable path exists in said routing database to calculate a new connection path, minimizing connection setup delay and suited to the connection requirements, to establish the requested connection using the new path and to store the new path in the routing database to create a stored connection path, said path selection subsystem also being responsive to the existence of a stored connection path to calculate and store at least one alternative connection path associated with each stored connection path in the routing database;
• and a path recomputation subsystem for periodically recalculating stored connection paths stored in the routing database.

A system for a packet switching communication network having a plurality of nodes interconnected by transmission links, said system including a connection setup system for establishing a connection between an origin node and a destination node, comprising:

• a routing database for storing previously established paths between different ones of said nodes;
• a path selection subsystem responsive to a connection request for determining whether said routing database contains a previously established stored path satisfying the requirements of the connection request, said path selection subsystem being responsive to a determination that a suitable path exists in said routing database to establish the requested connection using the previously established path, said path selection subsystem being responsive to a determination that no suitable path exists in said routing database to calculate a new path minimizing connection setup delay and satisfying the connection requirements, to establish the requested connection using the new path and to store the new path in the routing database, said path selection subsystem also being responsive to the existence of a stored path to calculate and store an alternative path associated with each stored path in the routing database;
• and
• periodically recalculating the paths stored in the routing database.

A method of determining an optimal path between an origin node and a destination node in a packet switching communication network comprising a plurality of nodes interconnected with transmission links, said method involving the steps of:

• for each connection request, selecting a pre-calculated path satisfying said connection request in the routing database;
• if no pre-calculated path satisfying the connection request is already stored in the routing database, calculating a path satisfying said connection request and storing said path within the routing database;
• recalculating the paths stored in the routing database periodically;
• and
• recalculating the paths stored in the routing database in response to at least one pre-determined event in the network.